1. Field of the Invention
The invention relates to a substrate-container measuring device and to a substrate-container measuring jig. Particularly, the invention relates to a substrate-container measuring device and a substrate-container measuring jig, which are useful for accurately measuring outer dimensions of a substrate-container used for transporting substrates in a factory for manufacturing semiconductor devices or liquid-crystal display devices.
2. Description of the Background Art
In a factory for manufacturing semiconductor devices or liquid-crystal display devices, substrates are usually transported while housed in a substrate-container. A FOUP (front opening unified pod) for wafers having a size of 300 mm or more is conceived as a container to be utilized for such an application. The FOUP has a door in the front thereof, and a plurality of substrates are housed in the FOUP. After being housed, the substrates are sealed and can be automatically transported at high speed.
As a result of being housed in the FOUP, the substrates are transported to a substrate processing system without being exposed to an atmosphere having a low level of cleanliness. In an individual processing device, the door of the FOUP is opened and closed by an opener (or a load port) such that an internal space of the FOUP is brought in mutual communication with only an internal space of the substrate processing system. The inside of an enclosure of the substrate processing system is maintained at a high level of cleanliness. Under the transport method using a FOUP, substrates are sequentially advanced through a plurality of processes without being exposed to an atmosphere having a low level of cleanliness by employing a mini-environment.
For managing a FOUP appropriately such that substrates are maintained at a high level of cleanliness in a low-level environment and problems in relation to opening and closing actions of FOUP or automatic transportation are prevented from arising, it is required to accurately measure outer dimensions of the FOUP. A known method for measuring outer dimensions of a three-dimensional object, such as a FOUP, is a contact-type measurement method for mechanically measuring dimensions of the object by means of actuating a measurement probe or the like through use of a robot.
However, various difficulties are encountered in achieving extremely high measurement precision through use of the contact-type measurement method. For this reason, as the degree of measurement precision required for managing a FOUP is increased, managing the FOUP with use of the measurement method involving use of a mechanical contact-type probe becomes more difficult.
In order to measure a three-dimensional object with high accuracy, utilization of a non-contact-type measurement method using an optical distance-measuring sensor is conceivable. However, in relation to a measurement method using a distance-measuring sensor, a tradeoff exists between a focal depth of a distance-measuring sensor and the accuracy of dimensional measurement. For this reason, when the method using a distance-measuring sensor is applied to dimensional measurement of a FOUP, a measurable range becomes considerably narrow, thereby posing great difficulty in capturing an object of measurement within the measurable range.